HCA: Hermit Crab Association

I don’t currently have hermit crabs, but I have another land crab species that is kept in a similar way(just much larger). I know the general recommendation for heating is having a UTH on the side of the tank which I do, but was thinking… wouldn’t it be more natural to have the heat on top facing down? What would the downsides be of taking the UTH and putting it on my lid facing down? I have a mist system and feel the humidity shouldn’t be too hard to keep up. It would also help keep the pools fairly warm when they start getting a little colder during winter. With this, he could burrow as deep as he likes to cool off or come up to get warm as they would in the wild.

Heat rises, so the heat from the UTH would rise up and not sink down into the tank. Some people use heat lamps, but those tend to decrease humidity.